JP4188872B2 - Gas detector, vehicle auto ventilation system - Google Patents

Description

  The present invention relates to a gas detection device and a vehicle autoventilation system that detect a change in the concentration of a specific gas in an environmental gas using a gas sensor element, and in particular, when entering a space in which a specific gas stays, such as a tunnel. The present invention relates to a gas detection device and a vehicle auto-ventilation system that can detect this.

  Conventionally, gas sensor elements using metal oxide semiconductors such as WO3 and SnO2 are known. These sensor resistance values change due to changes in the concentration of oxidizing gases such as NOx in environmental gases and reducing gases such as CO and HC (hydrocarbon). Changes in concentration can be detected. There is also known a gas detection device that obtains a sensor output value corresponding to the sensor resistance value of such a gas sensor element using an electronic circuit and detects a change in the concentration of a specific gas from the change in the sensor output value. Furthermore, various control systems using this gas detection device, for example, a vehicle auto ventilator that performs flap opening / closing control for switching between introduction of outside air and introduction of inside air in accordance with the contamination status of outside air in the cabin A system or the like is known (see, for example, Patent Document 1).

  By the way, unlike general roadways that are open to the surroundings, for example, in tunnels and underground parking lots, exhaust gas stays inside, so reducing gases such as NOx and other reducing gases such as NOx and CO in the environmental gas. The gas concentration is high. Therefore, it is desirable to detect such a situation when the vehicle enters such an environment and perform control to switch and rotate the flap to the inside air circulation side.

  Therefore, in Patent Document 1, “even at a general road, at an intersection with a large amount of traffic, etc., the gas concentration may be as high as in a tunnel. In general, the gas concentration is substantially constant while the gas concentration varies greatly on general roads. (See the sixth paragraph), the following vehicle tunnel detection device has been proposed. That is, in this vehicle tunnel running detection device, the gas detection means for detecting the gas concentration is used, the output value sampled by the sampling means is larger than a predetermined threshold value, and the difference between the two output values before and after is predetermined. When it is within the range, a detection signal indicating that the vehicle is traveling in the tunnel is output.

Japanese Patent Laid-Open No. 5-58146 (FIG. 2)

  However, it has been found that the change in the concentration of NOx, CO, etc. in the tunnel tends to gradually increase as it progresses through the tunnel, as shown in the lowermost graph of FIG. Therefore, as described above, the traveling detection apparatus for a vehicle tunnel in Patent Document 1 is based on the premise of the fact that the gas concentration is substantially constant in the tunnel, whereas the gas concentration largely fluctuates on a general road. Therefore, it is not possible to properly detect entry into the tunnel.

  The present invention has been made in view of such a problem, and even when entering a gas retention space such as a tunnel, a gas detection device capable of appropriately detecting this and a vehicle autoventilation using the same. The purpose is to provide a system.

  The solving means includes a gas sensor element whose sensor resistance value changes in accordance with a change in concentration of a specific gas in the environmental gas, an acquisition means for acquiring a sensor output value in accordance with the sensor resistance value, and the above-mentioned in the environmental gas. A second gas sensor element whose second sensor resistance value changes in accordance with a change in the concentration of the second specific gas other than the specific gas; and second acquisition means for acquiring a second sensor output value corresponding to the second sensor resistance value; The gas sensor element and the second gas sensor element using the duration of the change of the sensor output value in the high concentration direction and the second duration of the change of the second sensor output value in the second high concentration direction Is a staying space approach determining means for determining whether or not it has entered the gas staying space.

In the gas detection device of the present invention, the acquisition means and the second acquisition means acquire the sensor output value for the gas sensor element that reacts to the specific gas and the second sensor output value for the second gas sensor element that reacts to the second specific gas. To do. Then, using the duration of the change of the sensor output value in the high concentration direction and the second duration of the change of the second sensor output value in the second high concentration direction, the gas sensor element and the second The entrance of the gas sensor element is determined.
As described above, in tunnels and the like, concentrations of NOx, CO, etc. tend to gradually increase with progress. In particular, gasoline vehicles and diesel vehicles travel in tunnels where vehicles travel. For this reason, it originates from exhaust gas emitted from gasoline vehicles (specifically, reducing gases such as CO and HC) and exhaust gas emitted from diesel vehicles (specifically, oxidizing gases such as NOx). It has been found that the concentrations of gases having different properties tend to gradually increase as they progress through the tunnel. Therefore, if the sensor output value has a long duration of change in the high concentration direction, and the second sensor output value also has a long second duration of change in the second concentration high direction, Can be determined to have entered.

In the present specification, the gas retention space refers to a space where the specific gas and the second specific gas are retained, specifically, assuming NOx as the specific gas and CO, HC as the second specific gas. For example, a tunnel on a road, an underground parking lot, and a self-propelled parking lot in which the surroundings are likely to be blocked by a wall surface.
Further, as the acquisition means, it is only necessary to acquire sensor output values at appropriate intervals. Therefore, in addition to acquiring sensor output values every predetermined cycle time, acquisition intervals may vary. . However, it is preferable to acquire the data every predetermined cycle time because the time interval between the obtained sensor output values becomes constant, and the processing becomes easy.

  Note that the second acquisition unit only needs to acquire the second sensor output value at an appropriate time interval, and may acquire it at the same cycle time as the acquisition unit. Alternatively, the sensor output value may be the first output value. Alternatively, the second sensor output value may be obtained every second predetermined cycle time different from this. Furthermore, these acquisition time intervals may vary with time. However, in the case of acquiring at every predetermined time (every predetermined cycle time or every second predetermined cycle time), since the time interval between the obtained sensor output value and the second sensor output value is constant, the processing is easy. is there.

In the present specification, for convenience, the direction in which the sensor output value changes when the concentration of the specific gas increases is referred to as the high concentration direction.
Therefore, in the gas detection device in which the characteristics of the gas sensor element and the electronic circuit are configured so that the sensor output value increases when the concentration of the specific gas increases, the sensor output value indicates the sensor output value. The direction that becomes larger. On the contrary, in the gas detection device in which the sensor output value decreases when the concentration of the specific gas increases, the high concentration direction of the sensor output value refers to the direction in which the sensor output value decreases.
On the other hand, the low density direction refers to the direction opposite to the high density direction.

In the present specification, the same expression is used for the second gas sensor element.
That is, for the sake of convenience, the direction in which the second sensor output value changes when the concentration of the second specific gas increases in the second sensor output value is referred to as the second concentration high direction.
Therefore, in the gas detection device in which the characteristics of the second gas sensor element and the electronic circuit are configured so that the second sensor output value increases when the concentration of the second specific gas increases, the second sensor output value is the second sensor output value. The two-concentration high direction means a direction in which the second sensor output value increases. On the contrary, in the gas detection device in which the second sensor output value decreases when the concentration of the second specific gas increases, the second sensor output value is the second sensor output value. The direction that becomes smaller.
On the other hand, the second low concentration direction refers to a direction opposite to the high second concentration direction.

Further, in this specification, wind is an environmental gas generated by relative movement of the gas sensor element and the heater element, or the second gas sensor element and the heater element or the second heater element, and the environmental gas in contact therewith. The flow to the gas sensor element or the like. Accordingly, when the gas sensor element or the like does not move with respect to the ground, the environmental gas refers to the flow with respect to the ground and the gas sensor element or the like, as in the meaning of the normally used wind. On the other hand, when a gas sensor element or the like is mounted on an automobile or the like and moves with respect to the ground, it means a flow in which environmental gas moves relative to the gas sensor element or the like. Therefore, even if the environmental gas does not move with respect to the ground, the gas sensor element itself may move, so that when the gas sensor element or the like is viewed, the environmental gas flow seems to be generated. Including.
The wind-induced change is a change in the sensor output value caused by a change in the relative speed between the gas sensor element and the environmental gas. Therefore, for example, in addition to the case where the relative speed is increased, the case where the relative speed is decreased is included.

Furthermore, when the sensor output value changes in the high density direction due to the wind-induced change, the change direction of the relative speed (wind speed) is also the high density direction. That is, the relative speed change in the high density direction means a change in the relative speed in the direction in which the sensor output value changes in the high density direction. Therefore, for example, in a gas detection device configured to increase the sensor output value when the concentration of a specific gas increases, if the sensor output value increases when the wind speed increases, the wind speed is increased. The change in the increasing direction means that the wind speed changes in the high concentration direction.
Similarly, a change in the second sensor output value caused by a change in relative velocity with the environmental gas in contact with the second gas sensor element is referred to as a second wind-induced change. In addition, when the second sensor output value changes in the second high density direction due to the second wind-induced change, the change direction of the relative speed (wind speed) is also referred to as the second high density direction. That is, the relative speed change in the second high density direction refers to a change in relative speed in a direction in which the second sensor output value changes in the second high density direction.

Furthermore, among the wind-induced changes in the sensor output value, the change due to the wind when the sensor output value changes in the same direction as the sensor output value changes when the concentration of the specific gas increases. This is a wind-induced high direction change. Therefore, when a wind-induced high direction change occurs in the sensor output value, the sensor output value tends to change in the high concentration direction.
Conversely, the change caused by the wind when the sensor output value changes in the same direction that the sensor output value changes when the concentration of the specific gas decreases is called the wind-induced low direction change. And
Further, among the second wind-induced changes in the second sensor output value, the change direction of the second sensor output value is the same direction in which the second sensor output value changes when the concentration of the second specific gas increases. The second wind-induced change in the case of changing to is referred to as a second wind-induced high direction change. Accordingly, when the second wind output high direction change occurs in the second sensor output value, the second sensor output value tends to change in the second density high direction.
Conversely, the second wind-induced change occurs when the change direction of the second sensor output value changes in the same direction as the second sensor output value changes when the concentration of the second specific gas decreases. Is the second wind-induced change in the lower direction.

  Further, although depending on the correlation between the concentration change of the specific gas and the concentration change of the second specific gas, the second sensor resistance value of the second gas sensor element is increased by increasing the concentration of the second specific gas. The direction in which the sensor resistance value of the (first) gas sensor element changes and the direction in which the concentration of the specific gas changes (concentration high direction), or the second sensor resistance value of the second gas sensor element, It is preferable to select the second gas sensor element so that either the direction changing with the increase of the wind speed or the direction in which the sensor resistance value of the first gas sensor element changes with the increase of the wind speed has different characteristics. This is because it becomes easy to separate the concentration change of the specific gas and the second specific gas from the change of the wind speed.

  Further, in the gas detection device, when the duration continues for a predetermined period or more, and the second duration is equal to or longer than a second allowable period and less than the second predetermined period, at least the second sensor output When the value continuously changes in the second concentration high direction, the duration continues for the second extension period until the second duration becomes equal to or longer than the second predetermined period. When the second continuation period continues for the second predetermined period or longer and the continuation period is equal to or longer than the first allowable period and less than the predetermined period, the sensor output value increases in the direction of increasing the density. When the change occurs continuously, a deviation allowing means for regarding that the second continuation period is continued for the second predetermined period or more over the first extension period until the continuation period becomes the predetermined period or more. Including gas detection equipment It may be set to be.

Assuming that the gas sensor element reacts to oxidizing gas and the second gas sensor element reacts to reducing gas, when a vehicle equipped with a gas detection device enters a gas retention space such as a tunnel, the sensor resistance value of the gas sensor element The state of the change and the change of the second sensor resistance value of the second gas sensor element are not necessarily the same. In other words, there may be a case where the periods in which the changes occur are shifted from each other, such that one starts to change first and the other changes later.
In this way, when there is a shift in the timing of the change, the second continuous period is still the second continuous period for the change of the second sensor output value even if the continuous period is equal to or longer than the predetermined period. 2 It may not arrive within a predetermined period. In such a case, it is not appropriate to judge that the tunnel has not been entered. Therefore, when waiting for a while, the second continuation period may be longer than the second predetermined period. However, at this point, the sensor output value changes its tendency to change, and if it is determined that there is no change, the sensor output value does not change in the high concentration direction at this point, so the change continues. In some cases, it is determined that there is no duration. As a result, the sensor output value continues to change in the high concentration direction over a predetermined period, and the second sensor output value also changes in the second high concentration direction over the second predetermined period. It may become impossible to determine that the vehicle has entered the tunnel due to a shift in the time of change.

On the other hand, in the gas detection device of the present invention, when the duration of the sensor output value becomes a predetermined period, the second duration of the second sensor output value is greater than or equal to the second allowable period and less than the second predetermined period. In this case, it waits to determine whether or not the gas has entered the gas retention space for at least the second extension period. That is, during the second extension period, the continuous period is regarded as continuing for a predetermined period or more regardless of whether or not the sensor output value continues in the high concentration direction. Therefore, in the second extension period, when the second sensor output value continues to change and finally reaches the second predetermined period, it is considered that the continuous period also continues for the predetermined period. It is possible to determine that the vehicle has entered the stay space by the stay space entry determination means. Thus, it is possible to appropriately determine the entry into the staying space while allowing a difference in change between the sensor output value and the second sensor output value.
Conversely, when the second duration of the second sensor output value becomes the second predetermined period, the same applies to the case where the duration of the sensor output value is greater than or equal to the allowable period and less than the predetermined period.

Furthermore, in the gas detection device according to any one of the above, the sensor output value is used to determine whether the concentration of the specific gas is high or to indicate that the concentration is high, or to indicate that the concentration is low. Using the concentration high / low determination means for performing determination and the second sensor output value, the determination of the concentration high indicating that the concentration of the second specific gas has increased or the determination of low concentration indicating that the concentration has decreased is performed. a second concentration height determination means for performing, after it is determined that has entered the gas retaining space in the retaining space entry judging means determines the low the concentration of the specific gas in the concentration height determining means, and said second concentration at least one of a determination that a low the concentration of the second specific gas in the high and low determining means, and the retaining space entry canceling means for canceling the determination that has entered to the gas retention space, gas detection instrumentation comprising It may be set to be.

In a gas retention space such as a tunnel, the concentration of the specific gas and the second specific gas often decreases rapidly near the outlet. Therefore, if a decrease in the concentration of the specific gas or the second specific gas can be detected, it can be determined that the gas has left the gas retention space.
Therefore, in the gas detection device of the present invention, in the staying space entry cancellation unit, the determination of the concentration of the specific gas is low in the concentration level determination unit, and the determination of the concentration of the second specific gas is low in the second concentration level determination unit. The determination that the gas has entered the gas retention space is canceled by at least one of them. Thereby, it can be reliably detected that the gas stays out of the space.

Furthermore, in the gas detection device according to claim 3, after determining that the gas staying space has been entered by the staying space approach determining unit, the gas staying space has been entered by the staying space approach releasing unit. over retaining space entry time to cancel the decision, said that suppresses concentration low determination suppressing means the concentration low determination of the specific gas at a concentration elevation determination means, over the retaining space entry period, the second density height said second inhibit the density low determination of the specific gas the second density lower determination inhibition means for judging means may be a gas detecting device comprising a.

For example, in a region that is not a gas retention space, such as on a general road, when the concentration of the specific gas decreases, it is required to quickly determine that the concentration is low by the concentration high / low determination means. Similarly, when the concentration of the second specific gas decreases, it is required to quickly determine that the concentration is low by the second concentration high / low determination means. This is because appropriate gas detection is performed, and it is required to make an appropriate determination according to the concentration of the specific gas or the like. In particular, in a vehicle auto-ventilation system, it is known that opening a flap as much as possible and introducing outside air is preferable from the viewpoint of the health of passengers. It is preferable to determine.
On the other hand, there is a change in the concentration of the specific gas even in a gas retention space where the concentration of the specific gas is high. Therefore, when the concentration of the specific gas is still high, but the concentration is slightly low, if the sensor output value changes due to this change, the concentration of the specific gas may be erroneously determined to be low. The same applies to the second sensor output value, and there is a possibility that the second specific gas is erroneously determined to be the second concentration low.

  On the other hand, in the gas detection apparatus of the present invention, the low concentration determination suppression means suppresses the determination of the low concentration of the specific gas by the low concentration determination means during the stay space entry period. That is, when the gas detection device has entered the gas retention space, it is difficult for the concentration high / low determination means to make a determination of low concentration. Similarly, for the second sensor output value, the second concentration low determination suppression means suppresses the determination of the second specific gas concentration low by the second concentration low determination determination means over the staying space entering period. That is, when the gas detection device has entered the gas retention space, the second concentration high / low determination means makes it difficult for the low concentration determination to occur. For this reason, in the stay space entering period, the erroneous determination that the concentration of the specific gas and the second specific gas is low is prevented.

As a means for suppressing the determination of the low concentration of the specific gas in the low concentration determination suppressing means, any method can be used as long as the determination of the low concentration is finally suppressed, but the current reference value is calculated as a reference value. In the case of determining whether the concentration of the specific gas is high or low by comparing the current sensor output value with the current reference value, the reference value is set to There is a method of appropriately processing so as to obtain a value that is difficult to determine. More specifically, the calculation formula for calculating the reference value may be changed as appropriate, or the coefficient used in the calculation formula may be changed. The same applies to the second low concentration determination suppression means.

5. The gas detection apparatus according to claim 4, further comprising: a reference value calculation unit that calculates a current reference value; and a second reference value calculation unit that calculates a current second reference value, wherein the concentration The height determination means compares the current sensor output value with the current reference value to determine whether the concentration of the specific gas is high or low, and the second concentration high / low determination means The second sensor output value and the current second reference value are compared to determine whether the concentration of the second specific gas is high or low, and the low concentration determination suppressing means Reference value change suppression means for suppressing a change in the current reference value calculated by the value calculation means, wherein the second low concentration determination suppression means is the current first value calculated by the second reference value calculation means. 2 Second reference value change suppression that suppresses changes in the reference value May the gas detector is stepped.

The current sensor output value is compared with the current reference value, the concentration high / low determination means determines whether the concentration of the specific gas is high or low, and the current second sensor output value and the current second reference value are determined. In contrast, there is a case where the second specific gas level determination means determines whether the concentration of the second specific gas is high or low .
By the way, in a gas retention space such as a tunnel, a concentration change often occurs even when the concentration of a specific gas is high. Accordingly, since the sensor output value varies in accordance with the change in density, the reference value also varies. Then, for example, when the concentration of a specific gas changes from “very high” to “high”, the sensor output value changes in the direction of low concentration and the reference value also changes. It will be judged. In other words, it may be determined that the concentration of the specific gas is low even though the concentration of the specific gas is “high”. Then, when this gas detection device is used in a vehicle auto-ventilation system, there is a risk that the flaps are introduced into the outside air, and the outside air in a “high state” concentration of the specific gas may be introduced. The same applies to the second specific gas, the second sensor output value, and the like.

On the other hand, in the gas detection device of the present invention, the change in the reference value is suppressed by the reference value change suppressing means. For this reason, after it determines with the stay space approach determination means having entered into the gas stay space, the reference value is suppressed from changing. In general, the concentration of the specific gas gradually increases in the gas retention space, and therefore the sensor output value continues to change in the higher concentration direction even after the determination. On the other hand, the change of the reference value is suppressed and is close to the reference value at the time of determination. Therefore, after the sensor output value has greatly changed in the high concentration direction, the sensor output value has changed in the low concentration direction in response to the specific gas concentration changing from “very high” to “high”. However, in contrast with the reference value whose change has been suppressed, the concentration high / low determination means rarely determines that the concentration of the specific gas is low. Thus, it is possible to suppress erroneous determination that the concentration of the specific gas has decreased due to the concentration fluctuation of the specific gas in the gas retention space.
The same applies to the second specific gas, the second sensor output value, and the like.

  The gas detection device according to claim 5, wherein the reference value change suppression unit is a reference value calculation coefficient changing unit that changes a coefficient of a calculation formula used in the reference value calculation unit, and the second reference The value change suppression means may be a gas detection device which is second reference value calculation coefficient changing means for changing a coefficient of a calculation formula used in the second reference value calculating means.

In the gas detection device of the present invention, the coefficient of the calculation formula used in the reference value calculation means is changed. For this reason, it is possible to easily calculate the current reference value whose change is suppressed.
The same applies to the second specific gas, the second sensor output value, and the like.

  Furthermore, it is good to set it as the autoventilation system for vehicles containing the gas detection apparatus of any one of Claims 1-6.

  In these vehicle auto-ventilation systems, by using the gas sensor element and the second gas sensor element, a gas retention space such as a tunnel can be detected appropriately, so that the flap can be opened and closed appropriately.

(Embodiment)
An embodiment of the present invention will be described with reference to FIGS. First, FIG. 1 shows a circuit diagram and a block diagram of a gas detection device 210 of the present embodiment, and a schematic configuration of a vehicle auto-ventilation system 200 including the same. In this system 200, a gas detection device 210 that outputs a concentration signal LV according to a change in the concentration of a specific gas, and a flap 34 are rotated so that either the inside air intake duct 32 or the outside air intake duct 33 is connected to the duct 31. And an electronic control assembly 20 that controls the flaps 34 of the ventilation system 30 in accordance with the concentration signal LV.

First, the gas detection device 210 will be described. The gas detection device 210 includes a D-side gas sensor element 211, a G-side gas sensor element 221, and a heater element 202, and uses a gas sensor 201 that is arranged in one container while allowing outside air to flow in.
Among these, the D-side gas sensor element 211 reacts to the presence of an oxidizing gas component such as NOx in the gas to be measured (atmosphere in the present embodiment), and the D-side sensor resistance increases as the concentration of the oxidizing gas component increases. A D-side gas sensor element 211 of an oxide semiconductor of a type in which the value Rs1 increases is used. The gas sensor element 11 is disposed at a position close to the heater element 2, and is heated by energizing the heater element 2, thereby exhibiting an oxidizing gas detection capability.
On the other hand, the G-side gas sensor element 221 has different characteristics from the D-side gas sensor element 211, and reacts when there is a reducing gas component such as CO or HC (hydrocarbon) in the gas to be measured, thereby reducing the reducing gas. This is an oxide semiconductor gas sensor element in which the sensor resistance value Rs2 decreases as the component concentration increases. The G-side gas sensor element 221 is also disposed at a position close to the heater element 202 and is heated by the heater element 202 to exhibit the ability to detect reducing gases such as CO and HC.

In the gas detection device 210 of this embodiment, the D-side sensor output value Sd is obtained by the D-side sensor output value acquisition circuit 219 including the D-side gas sensor element 211, the sensor resistance value conversion circuit 214, the buffer 213, and the A / D conversion circuit 215. (N) is acquired. Among these, the sensor resistance value conversion circuit 214 divides the power supply voltage Vcc by the sensor resistance value Rs1 of the D-side gas sensor element 211 and the detection resistance value Rd1 of the detection resistor 212, and the sensor output potential Vs1 at the operating point Pd1. Output. For this reason, in the sensor resistance value conversion circuit 214, when the concentration of the oxidizing gas such as NOx increases, the sensor resistance value Rs1 of the D-side gas sensor element 211 increases, the sensor output potential Vs1 increases, and the obtained D-side The sensor output value Sd (n) is configured to increase.
The output of the buffer 213 is output as the current D-side sensor output value Sd (n) every predetermined cycle time (for example, 0.5 seconds) via the A / D conversion circuit 215, and is input to the microcomputer 216. 217 is input. n is a series of integers representing the order.

Further, in the gas detection device 210, the G side sensor output value Sg (n) is obtained by the G side sensor output value acquisition circuit 229 including the G side gas sensor element 221, the sensor resistance value conversion circuit 224, the buffer 223, and the A / D conversion circuit 225. ) To get. Among these, the sensor resistance value conversion circuit 224 divides the power source voltage Vcc by the sensor resistance value Rs2 of the G-side gas sensor element 221 and the detection resistance value Rd2 of the detection resistor 222, and the sensor output potential Vs2 at the operating point Pd2. Output. Therefore, in the sensor resistance value conversion circuit 224, when the concentration of reducing gas such as CO increases, the sensor resistance value Rs2 of the G-side gas sensor element 221 decreases, the sensor output potential Vs2 decreases, and the obtained G side The sensor output value Sg (n) is configured to decrease.
The output of the buffer 223 passes through the A / D conversion circuit 225, and at the same predetermined cycle time (for example, 0.5 seconds) as the D-side sensor output value Sd (n), the current G-side sensor output value Sg ( n) and input to the input terminal 227 of the microcomputer 216. When comparing the D-side sensor output value Sd (n), the G-side sensor output value Sg (n), etc., the same symbol such as “n” is used to indicate that the values are obtained at the same timing. .

Therefore, in the present embodiment, the D-side sensor output value Sd (n) increases as the oxidizing gas concentration increases. A direction in which the value of the output value Sd (n) increases. On the other hand, the direction of decreasing density is the direction in which the D-side sensor output value Sd (n) decreases.
In the present embodiment, of the wind-induced changes that occur in the D-side sensor output value Sd (n), the wind-induced high-direction change is the direction in which the D-side sensor output value Sd (n) increases (concentration high direction). Therefore, the change occurs when the relative speed between the D-side gas sensor element 211 and the like and the outside air increases (when the wind speed increases).

On the other hand, since the G-side sensor output value Sg (n) becomes a small value when the concentration of the reducing gas increases, the second high concentration direction of the G-side sensor output value Sg (n) is the G-side sensor output value Sd. The direction in which the value of (n) decreases. On the other hand, the second low concentration direction is the direction in which the G-side sensor output value Sg (n) increases.
Of the second wind-induced changes occurring in the G-side sensor output value Sg (n), the second wind-induced high direction change is a direction in which the G-side sensor output value Sg (n) decreases (second concentration high direction). ) Indicates a change that occurs when the relative speed between the G-side gas sensor element 211 and the like and the outside air decreases (when the wind speed decreases).

Further, from the output terminal 218 of the microcomputer 216, either a high density signal (LV = 1) or a low density signal (LV = 0) for controlling the electronic control assembly 20 is output. The electronic control assembly 20 controls a flap 34 of a ventilation system 30 that controls the inside air circulation and outside air intake of the automobile. Specifically, in this embodiment, the ventilation system 30 includes a duct 31 connected to the interior of the automobile interior, and a duct 31 for taking in and circulating the inside air, and a duct 33 for taking in outside air. The flap 34 for switching between is controlled.
In the electronic control assembly 20, the flap drive circuit 21 operates the actuator 22 and rotates the flap 34 in accordance with the concentration signal LV from the output terminal 218 of the microcomputer 216, and the inside air intake duct 32 and the outside air intake duct. Any one of 33 is connected to the duct 31.
In this embodiment, since the two gas sensor elements 211 and 221 are used, the D-side gas detection signal from the D-side gas sensor element 211 is in a clean air detection state (low concentration: LVd = 0), as will be described later. In addition, the concentration signal LV becomes low concentration (LV = 0) only when the G side gas detection signal from the G side gas sensor element 221 is also in a clean air detection state (low concentration: LVg = 0) (FIG. 10: Steps T64 to T66).

  For example, as shown in the flowchart of FIG. 2, after performing the initial setting in step S1, the density level signal LV is acquired in step S2, and whether or not the density signal LV is high level (LV = 1) in step S3. That is, it is determined whether or not a high density signal is being generated. Here, when No, that is, when a low concentration signal is being generated (LV = 0), since the concentration of the specific gas is low, in step S4, the flap 34 is fully opened. Thereby, the flap 34 rotates, the outside air intake duct 33 is connected to the duct 31, and the outside air is taken into the vehicle interior. On the other hand, if Yes in step S3, that is, if a high concentration signal is being generated (LV = 1), the concentration of the specific gas outside the passenger compartment is high, and in step S5, the flap 34 is instructed to be fully closed. As a result, the flap 34 is rotated, the inside air intake duct 32 is connected to the duct 31, the introduction of the outside air is blocked, and the inside air is circulated.

  A fan 35 that pumps air is installed in the duct 31. The flap drive circuit 21 may open and close the flap 34 only according to the concentration signal LV. For example, a microcomputer or the like is used to indicate the concentration signal LV from the gas detection device 10 as well as the broken line in the figure. As shown, the flap 34 may be opened and closed in consideration of information from, for example, a room temperature sensor, a humidity sensor, and an outside air temperature sensor.

  In the microcomputer 216, the D-side gas sensor element is processed by processing the D-side sensor output value Sd (n) and the G-side sensor output value Sg (n) input from the input terminals 217 and 227 according to a flow described later. The change in concentration of the oxidizing gas component and the reducing gas component is detected from the sensor resistance values Rs1, Rs2 of 211 and the G-side gas sensor element 221 and changes thereof. Although not shown in detail, the microcomputer 216 has a known configuration, and includes a microprocessor that performs calculations, a RAM that temporarily stores programs and data, a ROM that stores programs and data, and the like. Further, a buffer including the buffers 213 and 223 and the A / D conversion circuits 215 and 225 can also be used.

By the way, when the gas detection device 210 (automotive ventilation system 200 for vehicles) having such a configuration is mounted on an automobile and traveled, the D-side sensor output value Sd (n) or the G-side sensor output value Sg (n). May cause a slowly changing phenomenon.
One of the cases where such a phenomenon occurs is when an automobile enters a tunnel. The tunnel does not have sufficient air flow, and tends to be a space in which gases such as NOx and CO stay, and the concentration of these gases tends to be higher than outside the tunnel. In addition, the concentration tends to increase with the progress of the car after entering, and for this reason, the D-side sensor output value Sd (n) and the G-side sensor output value Sg (n) gradually change in the high concentration direction. .

Another case is due to a change in relative speed between the environmental gas and the gas sensor element 211 and the second gas sensor element 221 due to a change in the vehicle speed or the like. In this case, there is a phenomenon in which the obtained D-side sensor output value Sd (n) gradually changes even though the oxidizing gas concentration does not change. Similarly, a phenomenon occurs in which the obtained G-side sensor output value Sg (n) gradually changes despite no change in the concentration of the reducing gas. This phenomenon is observed when, for example, the vehicle travels at a relatively low speed in an urban area and then enters a highway to move at high speed, or vice versa.
This is because both the D-side gas sensor element 211 and the G-side gas sensor element 221 are heated by the heater element 022, so that the D-side gas sensor element 211 and the G-side gas sensor are changed depending on the change in the moving speed of the automobile and the change in the wind speed of the outside air. This is considered to be because the amount of heat per hour taken by the outside air from the element 221 and the heater element 202 changes, so that the temperatures of the D-side gas sensor element 211 and the G-side gas sensor element 221 change.

Among these, the sensor resistance value Rs1 of the D-side gas sensor element 211 changes not only due to the change in the concentration of the oxidizing gas but also due to the temperature change. Specifically, the D-side gas sensor element 211 of the present embodiment has a characteristic that the sensor resistance value Rs1 increases when its own temperature decreases. Therefore, when the sensor resistance value conversion circuit 214 (D-side sensor output value acquisition circuit 219) of this embodiment is used, the D-side sensor output value Sd (n) also increases.
Therefore, during the period in which such a change occurs, there is a possibility that a change in the D-side sensor output value Sd (n) due to a change in the speed of the automobile or the like is erroneously detected as a change in the concentration of the oxidizing gas.
In the present embodiment, the D-side gas sensor element 211 is cooled, that is, the vehicle speed is increased or the wind speed is increased, and the relative speed between the D-side gas sensor element 211 and the outside air is increased. In this case, the D-side sensor resistance value Rs1 of the D-side gas sensor element 211 changes in the increasing direction, and the D-side sensor output value Sd (n) also rises, so that an erroneous detection that the concentration of the oxidizing gas has increased is detected. It is easy to produce. That is, when the wind speed increases, it is easy to erroneously detect that the concentration of the oxidizing gas has changed in the high concentration direction.

Similarly, the sensor resistance value Rs2 of the G-side gas sensor element 221 changes not only with the concentration change of the reducing gas but also with the temperature change. Specifically, the G-side gas sensor element 221 has a characteristic that the sensor resistance value Rs2 decreases as its own temperature increases. Therefore, when the sensor resistance value conversion circuit 224 (G-side sensor output value acquisition circuit 229) is used, the G-side sensor output value Sg (n) also decreases.
Therefore, when the G-side gas sensor element 221 is warmed, that is, when the vehicle speed is reduced or the wind speed is reduced, the relative speed between the G-side gas sensor element 221 and the outside air changes. Since the G-side sensor resistance value Rs2 of the G-side gas sensor element 221 changes in a decreasing direction and the G-side sensor output value Sg (n) also decreases, it is easy to erroneously detect that the concentration of the reducing gas has increased. . That is, when the wind speed is lowered, it is easy to erroneously detect that the concentration of the reducing gas has changed in the second concentration high direction.

  Therefore, in the gas detection device 210 of this embodiment, the control in the microcomputer 216 is performed as shown in the flowcharts of FIGS. As will be described below, the gas detection device 210 of the present embodiment can detect an increase in the concentration of oxidizing gas and reducing gas in the atmosphere by using two gas sensor elements 211 and 221. Detecting the influence on the D-side sensor output value Sd (n) and G-side sensor output value Sg (n) due to changes in the vehicle speed or wind speed of the automobile, compensating for this, and continuing gas detection appropriately Can do. Furthermore, it is possible to detect whether or not the gas has entered a gas retention space where the concentrations of both the oxidizing gas and the reducing gas, such as a tunnel, are rising (hereinafter also referred to as tunnel detection).

First, when the automobile engine is driven, the control system is started. The D side and G gas sensor elements 211 and 221 are respectively heated by the heater element 202 and wait for an active state. First, at step T11, initialization is performed.
As an initial setting, the D-side and G-side base sensor values Bd (0) and Bg (0) are used as the initial D-side and G-side sensor output values Sd ( 0) and Sg (0) are stored (Bd (0) = Sd (0), Bg (0) = Sg (0)). Further, a low density signal is generated as the density signal LV. Specifically, the density signal LV is set to a low level (LV = 0).

On the other hand, in the gas detection apparatus 210 of this embodiment, the control in the microcomputer 216 is performed as shown in the flowcharts of FIGS.
First, when the automobile engine is driven, the control system is started. After the gas sensor element 11 is heated by the heater element 2 and becomes active, first, initial setting is performed in step S11. As an initial setting, the initial sensor output value S (0) when the gas sensor element 11 is activated is stored as the base value B (0) (B (0) = S (0)). Further, in order to prevent an inappropriate value from being calculated in step S13 described later, S (−7) = S (−6) =... = S (−1) = S (0) is set. Further, a low density signal is generated as the density signal LV. Specifically, the density signal LV is set to a low level (LV = 0).

  Further, as shown in FIG. 3, the tunnel detection flag TN is set to TN = 0, the tunnel end recognition flag TNE is set to TNE = 0, the monitoring time counter C0 is set to C0 = 0, and the D side and G side inclination recognition counters C1, C2 is set to C1 = C2 = 0, D side and G side wind compensation values VADD and VADG are set to VADD = VADG = 0, D side and G side wind detection flags Wd and Wg are set to Wd = Wg = 0, holding counter Cd, Cg is set to Cd = Cg = 0.

Next, the process proceeds to steps T12 and T13, and as described above, the D-side sensor output value Sd (n) and the G-side sensor output value Sg (n) are acquired.
Next, the process proceeds to step T14, where it is determined whether it is time to monitor the slopes of changes in the D-side sensor output value Sd (n) and the G-side sensor output value Sg (n). Specifically, it is determined whether or not the monitoring time counter C0 = 16. If No, that is, if this monitoring time counter C0 ≦ 15, the process proceeds to step T21, the monitoring time counter C0 is incremented by one (C0 = C0 + 1), and the process proceeds to step T24. On the other hand, if Yes, that is, C0 = 16, the process proceeds to step T15, and first, the monitoring time counter C0 is cleared (C0 = 0).
Therefore, in the gas detection device 210 according to the present embodiment, while the D-side sensor output value Sd (n) and the G-side sensor output value Sg (n) are acquired in Steps T12 and T13, Step T15 is performed once every 16 times. Then, the wind correction end determination and tunnel / wind detection described later are performed.

  Progressing to step T16 following step T15, it is checked whether or not the gas detection device 210 of the present embodiment is determined to be located in a gas retention space such as in a tunnel (the presence or absence of tunnel detection). Specifically, it is determined whether or not tunnel detection flag TN = 1. Here, if No, that is, if tunnel detection is not in progress, the process proceeds to step T17, where D-side inclination & wind correction end determination (step T17), G-side inclination & wind correction end determination (step T18), D, G After performing processing by subroutines of sensor change timing deviation recognition (step T19) and tunnel / wind detection by the D and G sensors (step T20), the process proceeds to step T24. These subroutines will be described later.

  On the other hand, when the tunnel is being detected (Yes), the process proceeds to step T25. During tunnel detection, as described later, both the D-side sensor output value Sd (n) and the G-side sensor output value Sg (n) gradually change in the high concentration direction and the second high concentration direction, respectively. However, since the values are sufficiently shifted in the high density direction and the second high density direction, the processes related to wind correction, tunneling, and wind detection in steps T17 to T20 are not necessary.

In step T24, it is determined whether or not the tunnel detection flag TN = 1. If the tunnel is being detected (Yes), the process proceeds to step T25. If the tunnel is not being detected (No), the process proceeds to step T26.
In step T25, coefficients used in the calculation formulas for the D-side base value Bd (n) and the G-side base value Bg (n) calculated in steps T314, T317 (see FIG. 10) and T514, T517 (see FIG. 11) described later. Kd, Hd, Kg, and Hg are set. Specifically, Kd = k1, Hd = h1, Kg = k4, Hg = h4.
On the other hand, also in step T26, coefficients Kd, Hd, Kg, and Hg are set. Specifically, Kd = k2, Hd = h2, Kg = k5, Hg = h5.

Note that 0 <k1 <k2 <1, 0 <h1 <h2 <1, 0 <k4 <k5 <1, 0 <h4 <h5 <1. As will be described later, in the calculation formula for the D-side base value Bd (n) (steps T314 and T317), the smaller the coefficients Kd and Hd, the slower the change in the D-side base value Bd (n). Similarly, regarding the G-side base value Bg (n), in the calculation formula (steps T514 and T517), the smaller the coefficients Kg and Hg, the slower the change in the G-side base value Bg (n).
Therefore, if it is determined in steps T16 and T24 that the tunnel is being detected (Yes), the D-side base value Bd calculated in steps T314 and T317 is compared with the case where the tunnel is not being detected (No). (N) changes slowly. Further, the G-side base value Bg (n) calculated in steps T514 and T517 is also slowly changed.

Thereafter, in either case, the process proceeds to step T31, and in this subroutine, the D-side base value Bd (n) is calculated (see FIG. 10).
In the subroutine of Step T31, first, in Step T311, it is determined whether or not 4 samplings or more have elapsed after the acquisition of the D-side sensor output value Sd (n) is started. As will be described later, when calculating the D-side base value Bd (n) (see step T314), the past D-side sensor output value Sd (n-4) for 4 samplings is used. This is because this Sd (n-4) is not obtained.
Therefore, if 4 samplings or more have not elapsed (No), the D-side base value Bd (n) is calculated in step T317, and the process returns to the main routine. Specifically, it is based on an equation of Bd (n) = Bd (n−1) + Kd [Sd (n) −Bd (n−1)] − Hd [Sd (n) −Sd (0)].

  On the other hand, if four or more samplings have elapsed since the start of acquisition (Yes), the process proceeds to step T312 to determine whether or not the tunnel end recognition flag TNE is TNE = 1. The tunnel end recognition flag TNE is a flag that is set to TNE = 1 in steps T39 and T59, which will be described later, and is a flag that indicates the end of tunnel detection, that is, that the vehicle has exited from the gas retention space. The tunnel end recognition flag TNE and the above-described tunnel detection flag TN are flags commonly used for processing the two sensor output values Sd (n) and Sg (n).

If it is determined in step T312 that TNE = 0 (No), the process proceeds to step T313, and the D-side base value Bd (n−1) obtained in the previous time (previous cycle) is used as the current D-side sensor output. Compare with the value Sd (n). In the present embodiment, the D-side sensor output value Sd (n) becomes a large value when the concentration of the oxidizing gas increases. That is, the direction in which the D-side sensor output value Sd (n) increases is the high density direction. Further, in the vehicle auto-ventilation system 200, it is important to be able to close the flap 34 quickly and accurately to circulate the inside air when the concentration of the oxidizing gas increases.
By the way, as will be described later (see steps T32, T34, and T40), the D-side difference value Dd (n) between the D-side sensor output value Sd (n) and the D-side base value Bd (n) is used to oxidize. Determine the gas concentration level.

  Therefore, the D-side base value Bd (n−1) obtained last time is used as the D-side sensor output value Sd (n) in order to quickly capture the increase in the D-side sensor output value Sd (n) due to the increase in the concentration of the oxidizing gas. If it is the above value (No in step T313: Bd (n−1) ≧ Sd (n)), the process proceeds to step T316 to forcibly set the D-side base value Bd (n) to the D-side sensor. It matches the output value Sd (n). When the value of the D-side sensor output value Sd (n) increases (changes in the direction of high concentration), it is determined early at Step T40, that is, Dd (n) = Sd (n) −Bd (n )> TH21 in order to avoid a state in which the D-side base value Bd (n) is larger than the D-side sensor output value Sd (n) (Bd (n)> Sd (n)). Thereafter, the process returns to the main routine.

  On the other hand, if it is determined in step 313 that Bd (n−1) <Sd (n) (Yes), the process proceeds to step T314, the D-side base value Bd (n) is calculated, and the process returns to the main routine. . Specifically, it is based on the equation Bd (n) = Bd (n−1) + Kd [Sd (n) −Bd (n−1)] − Hd [Sd (n) −Sd (n−4)] + VADD.

  In the above formula, the fourth term is the D-side wind compensation value VADD. In this equation, since the D-side wind compensation value VADD appears in the equation, it seems that correction is always performed by changes in the wind speed. However, in step T704 (see FIG. 6), which will be described later, when correction for the D-side base value Bd (n) is not necessary, the D-side wind compensation value VADD is set to VADD = 0, and substantially no wind correction is performed. I'm trying not to be.

On the other hand, if it is determined in step T312 that TNE = 1 (Yes), the process proceeds to step T315, where the tunnel end recognition flag TNE is set to TNE = 0 to prepare for the next tunnel end recognition.
Subsequently, the process proceeds to step T316, and the D-side base value Bd (n) is forcibly matched with the D-side sensor output value Sd (n). When the tunnel end recognition flag TNE is set to TNE = 1, as described later, it is detected using the G-side sensor output value Sg (n) that the vehicle has escaped from the gas retention space (step T59). Reference). At this time, it is considered that not only the reducing gas but also the concentration of the oxidizing gas is lower than the concentration in the gas retention space. Therefore, at this time, the D-side base value Bd (n) is matched with the D-side sensor output value Sd (n) so that the subsequent increase in the concentration of the oxidizing gas can be captured earlier. Thereafter, the process returns to the main routine.

  Next, in step T32, a D-side difference value Dd (n) is calculated. Specifically, it is calculated by the formula Dd (n) = Sd (n) −Bd (n). As described above, when the concentration of the oxidizing gas increases relatively rapidly, the D-side sensor output value Sd (n) increases (changes in the higher concentration direction), while the D-side base value Bd (n) Depending on the values of the coefficients Kd and Hd, it decreases away from the D-side sensor output value Sd (n) or follows slowly. For this reason, the D-side difference value Dd (n) increases due to the increase in the concentration of the oxidizing gas, and the increase in the concentration of the oxidizing gas can be captured.

In a succeeding step T33, it is determined whether or not the oxidizing gas is being detected. Specifically, whether or not the D-side gas detection signal LVd determined by the D-side sensor output value Sd (n) and indicating whether or not the concentration of the oxidizing gas is high is currently LVd = 1 (high concentration). Determine whether.
Here, when the D-side gas detection signal is LVd = 0 (low concentration) (No), the process proceeds to Step T40. On the other hand, if LVd = 1 (Yes), the process proceeds to step T34.

In Step T40, which proceeds after it is determined that the D-side gas detection signal LVd = 0, the D-side difference value Dd (n) is compared with the positive D-side first threshold value TH21.
Among these, when the D-side difference value Dd (n) is larger than the D-side first threshold TH21 (Yes in step T40: Dd (n)> TH21), that is, the D-side sensor output value Sd (n) is on the D side. If the base value Bd (n) is larger than the predetermined value (TH21), the process proceeds to step T41. In step T41, it is assumed that an increase in the concentration of the oxidizing gas is detected. Specifically, LVd = 1 is generated instead of the current LVd = 0 as the D-side gas detection signal LVd. The fact that the D-side difference value Dd (n) has increased indicates that the value of the D-side sensor output value Sd (n) has increased, that is, has changed in the high density direction. Then, it progresses to step T43.
Conversely, when the D-side difference value Dd (n) is equal to or less than the D-side first threshold value TH21 (No), in step ST42, it is assumed that clean air is maintained for the oxidizing gas, and the current LVd = Maintain 0 and go to step T43.

On the other hand, in step T34, which proceeds after it is determined that the D-side gas detection signal LVd = 1, the D-side difference value Dd (n) is compared with the positive D-side second threshold value TH22. Here, the D-side second threshold value TH22 is smaller than the D-side first threshold value TH21 (TH22 <TH21). By setting the two threshold values TH21 and TH22 in such a relationship, the switching of the D-side gas detection signal LVd can have a hysteresis characteristic to prevent chattering.
Among these, when the D-side difference value Dd (n) is larger than the D-side second threshold value TH22 (Yes in step T34: Dd (n)> TH22), that is, the D-side sensor output value Sd (n) is on the D side. When the state that is larger than the base value Bd (n) by a predetermined value (TH22) is maintained, the process proceeds to step T35, where it is detected that the state in which the concentration of the oxidizing gas is maintained high is present. LVd = 1 is maintained, and the process proceeds to Step T43.
Conversely, if the D-side difference value Dd (n) is equal to or less than the D-side second threshold value TH22 (No), it is assumed in step T36 that a decrease in the concentration of the oxidizing gas, that is, clean air is detected, and the D-side gas is detected. As the detection signal LVd, LVd = 0 is generated instead of the current LVd = 1, and the process proceeds to Step T37. The fact that the D-side difference value Dd (n) has become smaller indicates that the value of the D-side sensor output value Sd (n) has decreased, that is, has changed in the lower density direction.

In a succeeding step T37, it is determined whether or not the tunnel detection flag TN = 1. If the tunnel is not being detected (No), the process proceeds directly to step T43. On the other hand, if the tunnel is being detected (Yes), the process proceeds to step T38.
In step T38, the fact that the tunnel is being detected is cleared. That is, the tunnel detection flag TN = 1 is changed to TN = 0. Further, in step T39, the tunnel end recognition flag TNE is set to TNE = 1, and the process proceeds to step T43. In a gas retention space such as a tunnel, the concentration of the oxidizing gas and the reducing gas is higher than in other places. Therefore, it is understood that the decrease in the concentration of the oxidizing gas can be detected in step T36, and that the gas staying space such as the tunnel has escaped.

  In any case, the current D-side sensor output value Sd (n) and the D-side base value Bd (n) are stored in step T43. This is because it is used for later detection, inclination detection, calculation of the D-side base value Bd (n), calculation of the D-side wind correction value VADD, and the like.

Subsequently, the process proceeds to step T51, and in this subroutine, the G-side base value Bg (n) is calculated in the same manner as the D-side base value Bg (n) (see FIG. 11).
In the subroutine of Step T51, first, in Step T511, it is determined whether or not 4 samplings or more have elapsed after the acquisition of the G-side sensor output value Sg (n) is started. As in the case of calculating the D-side base value, when calculating the G-side base value Bg (n) (see step T514), the past G-side sensor output value Sg (n-4) for four samplings is used. This is because this Sg (n-4) is not obtained for the period of 4 samplings.
Therefore, if 4 samplings or more have not elapsed (No), the G-side base value Bg (n) is calculated in step T517, and the process returns to the main routine. Specifically, according to the formula: Bg (n) = Bg (n-1) + Kg [Sg (n) -Bg (n-1)]-Hg [Sg (n) -Sg (0)].

On the other hand, when 4 samplings or more have elapsed from the start of acquisition (Yes), the process proceeds to step T512, and it is determined whether or not the tunnel end recognition flag TNE is TNE = 1.
If it is determined in step T512 that TNE = 0 (No), the process proceeds to step T513, and the previously obtained G-side base value Bg (n−1) is replaced with the current G-side sensor output value Sg (n). Compare. In the present embodiment, when the concentration of the reducing gas increases, the G-side sensor output value Sg (n) becomes a small value. In other words, the direction in which the G-side sensor output value Sg (n) decreases is the second high density direction. Further, in the vehicle auto-ventilation system 200, it is important to be able to close the flap 34 quickly and accurately to circulate the inside air even when the concentration of not only the oxidizing gas but also the reducing gas increases.
By the way, as will be described later (see steps T52, T54, and T60), the G-side difference value Dg (n) between the G-side sensor output value Sg (n) and the G-side base value Bg (n) is used. Determine the gas concentration level.

  Therefore, the G-side base value Bg (n−1) obtained last time is used as the G-side sensor output value Sg (n) in order to quickly capture the decrease in the G-side sensor output value Sg (n) due to the increase in the concentration of the reducing gas. If it is the following value (No in step T513: Bg (n−1) ≦ Sg (n)), the process proceeds to step T516 to force the G-side base value Bg (n) to the G-side sensor. The output value Sg (n) is matched. When the value of the G-side sensor output value Sg (n) decreases (changes in the second concentration high direction), Yes is determined early in step T60, that is, Dg (n) = Bg (n) −Sg. This is to avoid a state in which the G-side base value Bg (n) is smaller than the G-side sensor output value Sg (n) (Bg (n) <Sg (n)) so that (n)> TH23. . Thereafter, the process returns to the main routine.

  On the other hand, if it is determined in step 513 that Bg (n−1)> Sg (n) (Yes), the process proceeds to step T514, the G-side base value Bg (n) is calculated, and the process returns to the main routine. . Specifically, Bg (n) = Bg (n−1) + Kg [Sg (n) −Bg (n−1)] − Hg [Sg (n) −Sg (n−4)] − VADG .

  In the above expression, the fourth term is the G-side wind compensation value VADG. In this equation, since the G-side wind compensation value VADG appears in the equation, it seems that correction is always performed by a change in wind speed. However, when correction for the G-side base value Bg (n) is not required in Step T804, which will be described later, the G-side wind compensation value VADG is set to VADG = 0 so that the wind correction is not substantially performed. .

On the other hand, if it is determined in step T512 that TNE = 1 (Yes), the process proceeds to step T515, where the tunnel end recognition flag TNE is set to TNE = 0 to prepare for the next tunnel end recognition.
Subsequently, the process proceeds to step T516 where the G-side base value Bg (n) is forcibly matched with the G-side sensor output value Sg (n). When the tunnel end recognition flag TNE is set to TNE = 1, as described later, it is detected using the D-side sensor output value Sd (n) that the vehicle has escaped from the gas retention space (step T39). See also). At this time, it is considered that not only the oxidizing gas but also the concentration of the reducing gas is lower than the concentration in the gas retention space. Therefore, if TNE = 1, the G-side base value Bg (n) is matched with the G-side sensor output value Sg (n), and the subsequent increase in the concentration of the reducing gas is captured earlier. Thereafter, the process returns to the main routine.

  Next, in step T52, a G-side difference value Dg (n) is calculated. Specifically, it is calculated by the formula Dg (n) = Bg (n) −Sg (n). As described above, when the concentration of the reducing gas increases relatively rapidly, the G-side sensor output value Sg (n) decreases (changes in the second high concentration direction), while the G-side base value Bg (n). Depends on the values of the coefficients Kg and Hg, but increases away from the G-side sensor output value Sg (n) or follows slowly. For this reason, the G-side difference value Dg (n) increases due to the increase in the concentration of the reducing gas, and the increase in the concentration of the reducing gas can be captured.

In a succeeding step T53, it is determined whether or not reducing gas is being detected. Specifically, whether or not the G-side gas detection signal LVg determined by the G-side sensor output value Sg (n) and indicating whether or not the concentration of the reducing gas is high is currently LVg = 1 (high concentration). Determine whether.
Here, when the G-side gas detection signal is LVg = 0 (low concentration) (No), the process proceeds to Step T60. On the other hand, if LVg = 1 (Yes), the process proceeds to step T54.

In step T60, which proceeds after it is determined that the G-side gas detection signal LVg = 0, the G-side difference value Dg (n) is compared with the positive G-side first threshold value TH23.
Among these, when the G side difference value Dg (n) is larger than the G side first threshold value TH23 (Yes in step T60: Dg (n)> TH23), that is, the G side sensor output value Sg (n) is on the G side. If the base value Bg (n) is smaller than the predetermined value (TH23), the process proceeds to step T61. In step T61, it is assumed that an increase in the concentration of the reducing gas is detected. Specifically, instead of the current LVg = 0, LVg = 1 is generated as the G-side gas detection signal LVg. The fact that the G-side difference value Dg (n) has increased indicates that the value of the G-side sensor output value Sg (n) has decreased, that is, has changed in the second high concentration direction. Thereafter, the process proceeds to step T63.
Conversely, when the G-side difference value Dg (n) is equal to or smaller than the G-side first threshold value TH23 (No), in step ST62, it is assumed that clean air is maintained for the reducing gas, and the current LVg = Maintain 0 and go to step T63.

On the other hand, in step T54, which has proceeded after determining that the G-side gas detection signal LVg = 1, the G-side difference value Dg (n) is compared with the positive G-side second threshold value TH24. Here, the G-side second threshold value TH24 is smaller than the G-side first threshold value TH23 (TH24 <TH23). This is to prevent chattering.
Among these, when the G side difference value Dg (n) is larger than the G side second threshold value TH24 (Yes in step T54: Dg (n)> TH24), that is, the G side sensor output value Sg (n) is on the G side. When the state smaller than the predetermined value (TH24) is maintained with respect to the base value Bg (n), the process proceeds to step T55, where it is detected that the state in which the concentration of the reducing gas is maintained high is present. LVg = 1 is maintained, and the process proceeds to Step T63.
Conversely, if the G-side difference value Dg (n) is equal to or less than the G-side second threshold value TH24 (No), it is assumed in step T56 that a reduction in reducing gas concentration, that is, clean air has been detected, As the detection signal LVg, LVg = 0 is generated instead of the current LVg = 1, and the process proceeds to Step T57. The fact that the G-side difference value Dg (n) has decreased is because the value of the G-side sensor output value Sg (n) has increased, that is, has changed in the direction of decreasing density.

In a succeeding step T57, it is determined whether or not the tunnel detection flag TN = 1. If the tunnel is not being detected (No), the process proceeds directly to step T63. On the other hand, when the tunnel is being detected (Yes), the process proceeds to step T58.
In step T58, the tunnel detection flag is cleared, that is, the tunnel detection flag TN is set to TN = 0. Further, in step T59, the tunnel end recognition flag TNE is set to TNE = 1, and the process proceeds to step T63. In a gas retention space such as a tunnel, the concentration of the oxidizing gas and the reducing gas is higher than in other places. Therefore, it is understood that the reduction in the concentration of the reducing gas has been detected in step T56, so that it has been escaped from the gas retention space such as the tunnel.

  In any case, the current G-side sensor output value Sg (n) and the G-side base value Bg (n) are stored in step T63. This is because it is used for later, inclination detection, calculation of the G-side base value Bg (n), calculation of the G-side wind correction value VADG, and the like.

  Thereafter, in step T64, it is determined whether or not both the oxidizing gas and the reducing gas have become clean air, specifically, whether or not LVd = 0 and LVg = 0. Here, if Yes, that is, if the concentrations of both the oxidizing gas and the reducing gas are reduced, the concentration signal LV is set to LV = 0 in step T65. On the other hand, while it is determined that No, that is, the concentration of at least one of the oxidizing gas and the reducing gas is high, LV = 1 is generated in step T66. Thereafter, after the elapse of a predetermined sampling time in step T67, the process returns to the above-described step T12, and thereafter, the processing after step T12 is repeatedly performed as described above.

Next, steps T17 to T20 that have not been described will be described in order.
In the D side inclination & wind correction end determination subroutine (see FIG. 6) in step T17, inclination detection using the D side sensor output value Sd (n) is performed in step T701. Specifically, the past D-side sensor output values Sd (n), Sd (n-16) and the positive predetermined value A1 for the current and 16 samplings are used, and Sd (n) -Sd (n-16)> It is determined whether or not A1. Here, it is determined whether or not the recent increase amount of the D-side sensor output value (inclination of change in the high concentration direction) exceeds a predetermined magnitude.
Here, when Yes, that is, when the increase slope is large, it is considered that the D-side sensor output value Sd (n) has been increasing in the period of 16 samplings (8 seconds = 16 × 0.5) up to the present. . Therefore, the process proceeds to step T702, the D-side inclination recognition counter C1 is incremented (C1 = C1 + 1), and the process returns to the main routine. Therefore, the value of the D-side inclination recognition counter C1 corresponds to the length of the period during which the D-side sensor output value Sd (n) continues to increase (change in the high density direction). On the other hand, when the increase amount (slope) is small (No), the process proceeds to step T703.

  In step T703, the D-side inclination recognition counter C1 is cleared (C1 = 0). Since the recent increase in the D-side sensor output value Sd (n) is considered to be small, in the middle of the increase / decrease phase, or rather decreased, at least the D-side sensor output value Sd (n) is clear. This is because it is judged that there is no upward trend.

Next, in step T704, the D-side wind compensation value VADD is set to VADD = 0. Thereby, the correction by the D-side wind compensation value VADD (see step T314, see FIG. 10) in the calculation formula of the D-side base value Bd (n) described above is substantially ended, and the process returns to the main routine. When No is determined in step T701, as described above, it is considered that the D-side sensor output value Sd (n) does not tend to increase recently. It is understood that the change of (n) in the high concentration direction has not occurred or has ended. Therefore, the D-side wind correction in the calculation of the D-side base value Bd (n) performed to suppress erroneous detection due to the change in the D-side sensor output value Sd (n) in the high density direction (see step T314). It is considered unnecessary to continue. For this reason, the correction is substantially not performed.
Further, in step T704, the D-side wind detection flag Wd is cleared and Wd = 0 is set. This is because the D-side sensor output value Sd (n) is not observed to change in the high density direction due to the wind speed change.

Subsequent to the processing in step T17, a G-side inclination & wind correction end determination subroutine (see FIG. 7) in step T18 is executed. In the subroutine of step T18, first, in step T801, inclination detection using the G-side sensor output value Sg (n) is performed. Specifically, it is determined whether or not Sd (n−16) −Sd (n)> A2. Here, it is determined whether or not the recent decrease amount of the G-side sensor output value (inclination of change in the second high density direction) exceeds a predetermined magnitude.
Here, if Yes, that is, if the gradient of decrease is large, it is considered that the G-side sensor output value Sg (n) has been in a decreasing trend in the period of 16 samplings to date. Therefore, the process proceeds to step T802, the G-side inclination recognition counter C2 is incremented (C2 = C2 + 1), and the process returns to the main routine. Therefore, the value of the G-side inclination recognition counter C2 corresponds to the length of the period during which the decrease (change in the second density high direction) of the G-side sensor output value Sg (n) continues. Become.
On the other hand, when the amount of decrease (slope) is small (No), the process proceeds to step T803.

  In step T803, the G-side inclination recognition counter C2 is cleared (C2 = 0). Since the recent decrease amount of the G-side sensor output value Sg (n) is considered to be small, in the middle of the increase / decrease phase, or rather increased, at least the G-side sensor output value Sg (n) is clear. This is because it is judged that there is no significant downward trend.

In step T804, the G-side wind compensation value VADG is set to VADG = 0. As a result, the correction by the G-side wind compensation value VADG (see step T514, FIG. 11) in the above-described equation for calculating the G-side base value Bg (n) is substantially terminated, and the process returns to the main routine. If the answer is No in step T801, it is considered that the G-side sensor output value Sg (n) does not tend to decrease recently. 2 It is understood that the change toward higher concentration did not occur or ended. Therefore, the G side wind correction (step T514) in the calculation of the G side base value Bg (n) performed to suppress the erroneous detection due to the change in the G concentration sensor output value Sg (n) in the second high concentration direction. It is considered unnecessary to continue. For this reason, the correction is substantially not performed.
Further, in step T804, the G-side wind detection flag Wd is cleared and Wd = 0 is set. This is because the G-side sensor output value Sg (n) is not changed in the second high concentration direction due to the wind speed change.

  Subsequent to the processing in step T18, the D and G sensor change timing deviation recognition subroutine (see FIG. 8) in step T19 is executed. In the subroutine of step T19, the D-side inclination recognition counter C1 in steps T901 to T906 becomes C1 = 5, but the G-side inclination recognition counter C2 does not reach C2 = 5 (C2 <5). Conversely, in steps T911 to T916, the G-side inclination recognition counter C2 becomes C2 = 5, but the D-side inclination recognition counter C1 does not reach C1 = 5 (C1 <5). It is divided roughly into.

  When an automobile enters a gas retention space such as a tunnel, the concentration of oxidizing gas gradually increases. Then, since the D-side sensor output value Sd (n) continues to increase gradually, it is continuously determined that the inclination of increase is large in the above-described step T701. As a result, in step T702, the D-side inclination recognition counter C1 is incremented, so that the value of the D-side inclination recognition counter C1 gradually increases. On the other hand, the concentration of the reducing gas also increases gradually. Accordingly, since the G-side inclination recognition counter C2 is also incremented in step T802, the value of the G-side inclination recognition counter C2 should gradually increase. However, the increase in the concentration of the oxidizing gas and the increase in the concentration of the reducing gas do not coincide with each other. The sensitivity of the D-side gas sensor element 211 with respect to the oxidizing gas and the sensitivity of the G-side gas sensor element 221 with respect to the reducing gas. The sensitivity does not match. Therefore, even when an automobile enters the tunnel, the state in which the value of the D-side inclination recognition counter C1 increases is not consistent with the state in which the value of the G-side inclination recognition counter C2 increases. In many cases, one of the behaviors increases with a delay. On the other hand, with respect to a gas sensor element (for example, the D-side gas sensor element 211) that has detected an increase in gas concentration from an early stage, the rate of increase in concentration gradually decreases, and eventually the concentration may remain substantially constant with a high concentration. . In this case, for example, it is determined as No in step S701, and there is a possibility that this cannot be detected even though the vehicle actually enters the tunnel.

Therefore, in the gas detection device 210 of the present embodiment, a time lag between the increase in the concentration of the oxidizing gas and the increase in the concentration of the reducing gas is allowed as follows.
First, in step T901, it is determined whether or not the D-side inclination recognition counter C1 is C1 = 5 and the G-side inclination recognition counter C2 is C2 ≧ 2. Here, in the case of Yes, that is, for the D-side sensor output value Sd (n), over a long period of time until C1 = 5 (specifically, a period of at least 16 × 5 = 80 samplings or more). The value maintains an increasing tendency (change in the higher concentration direction). On the other hand, the G-side sensor output value Sg (n) tends to decrease over a period until C2 ≧ 2 (specifically, a period of at least 16 × 2 = 32 samplings or more) ( If the second concentration is not sufficiently long, the process proceeds to step T902. Here, the D-side holding counter Cd is set to Cd = 3.

On the other hand, if it is determined No in step T901, the process proceeds to step T903. In step T903, it is determined whether the D-side holding counter Cd is Cd> 0 and the G-side inclination recognition counter C2 is C2> 0.
Here, when Yes, that is, when the D-side holding counter Cd has been set in the above-described step T902 and the G-side inclination recognition counter C2 is C2> 0 (in this case, the G-side inclination recognition is performed). If the counter C2 should be C2 ≧ 2, the process proceeds to step T904. In step T904, the D-side holding counter Cd is decremented (Cd = Cd−1). Subsequently, in step T905, the D-side inclination recognition counter C1 is forcibly set to C1 = 5.
On the other hand, if NO in step T903, that is, if at least one of Cd = 0 and C2 = 0 is satisfied, the D-side holding counter Cd is cleared in step T906 (Cd = 0).

  As a result of such processing, the G-side inclination recognition counter C2 becomes 5 when the G-side inclination recognition counter C1 becomes C1 = 5 first, but the G-side sensor output value Sg (n) continues to decrease. When> C2 ≧ 2 (for example, C2 = 2), the D-side holding counter Cd is given a grace period of 3 times (3 × 16 = 48 cycles). During this time, if C2 = 5 is satisfied, Yes is determined in step T201, which will be described later, and tunnel detection is performed in step T231. In this embodiment, by doing in this way, the time shift | offset | difference in the case where the density | concentration rise of oxidizing gas occurs first and the density | concentration increase of reducing gas occurs subsequently is permitted.

  Steps T911 to T916 are almost the same as steps T901 to T906. That is, in step T911, it is determined whether the G-side inclination recognition counter C2 is C2 = 5 and the D-side inclination recognition counter C1 is C1 ≧ 2. Here, in the case of Yes, that is, for the G-side sensor output value Sg (n), the value maintains a decreasing tendency (change in the second high concentration direction) over a long period until C2 = 5. is doing. On the other hand, the D-side sensor output value Sd (n) maintains an increasing tendency (change in the high concentration direction) over a period until C1 ≧ 2, but is still sufficiently long. If not, the process proceeds to step T912. Here, the G-side holding counter Cg is set to Cg = 3.

On the other hand, if it is determined No in step T911, the process proceeds to step T913. In step T913, it is determined whether or not the G-side holding counter Cg is Cg> 0 and the D-side inclination recognition counter C1 is C1> 0.
Here, if Yes, that is, if the G-side holding counter Cg has been set in the above-described Step T912 and the D-side inclination recognition counter C1 is C1> 0, the process proceeds to Step T914. In step T914, the G-side holding counter Cg is decremented (Cg = Cg−1). Subsequently, in step T915, the G-side inclination recognition counter C2 is forcibly set to C2 = 5.
On the other hand, if NO in step T913, that is, if at least one of Cg = 0 and C1 = 0, the G-side holding counter Cg is cleared in step T916 (Cg = 0).

  According to such processing, contrary to the above, the D-side sensor output value Sd (n) continues to increase when the G-side inclination recognition counter C2 first becomes C2 = 5, When the D-side inclination recognition counter C1 is 5> C1 ≧ 2 (for example, C1 = 2), the G-side holding counter Cg is given three grace periods. In the meantime, if C1 = 5 is satisfied, it is determined as Yes in step T201 and tunnel detection is performed in step T231 as described above. In this embodiment, by doing in this way, a time lag is allowed even when the concentration of the reducing gas first occurs and then the concentration of the oxidizing gas increases.

  Subsequent to the processing in step T19, a tunnel / wind detection subroutine (see FIG. 9) by the D and G sensors in step T20 is executed. The subroutine of step T20 is roughly divided into wind detection and wind compensation value calculation processing in steps T202 to T209, T215 to T219, T221, and T222, and tunnel detection processing in steps T231 to T234.

  First, in step T201, it is determined whether both the D-side inclination recognition counter C1 and the G-side inclination recognition counter C2 are 5 (C1 = 5 and C2 = 5). That is, the D-side sensor output value Sd (n) continued to change in the high concentration direction (increase direction) over a long period (at least 40 seconds = 16 × 5 × 0.5 seconds), and the G-side sensor output value Sg Similarly, it is determined whether or not (n) has been confirmed to have continued to change in the second high concentration direction (decreasing direction) over a long period (at least 40 seconds).

  Here, in the case of Yes, it proceeds to step T231, and it is assumed that tunnel detection is performed in step T231. Specifically, the tunnel detection flag TN is set to TN = 1. Both the D-side sensor output value Sd (n) and the G-side sensor output value Sg (n) continue to change in the high concentration direction and the second high concentration direction over a long period. This indicates that the concentration gradually increased over a long period of time, and this phenomenon is considered to be caused when the automobile enters a gas retention space such as a tunnel.

  Therefore, subsequently, in step T232, the two wind detection flags Wd and Wg are forcibly cleared (Wd = Wg = 0). As will be described later, the D-side and G-side wind detection flags Wd and Wg may be set after step T202. However, if it is determined Yes in T201 described above, the D-side sensor output value Sd (n) or the G-side sensor output value Sg (n) changes in the high concentration direction and the second high concentration direction over a long period. The reason for this is that it has entered the tunnel or the like, not due to the change in the wind speed, and even if wind detection is made (Wd = 1 or Wg = 1), it is understood that it was an error. It is.

  Subsequently, in step T233, the two inclination recognition counters C1 and C2 are both cleared (C1 = C2 = 0), and in step T234, the holding counters Cd and Cg are also cleared (Cd = Cg = 0). Since tunnel detection is performed in step T231, it is no longer necessary to maintain the values of these counters, and this is to prepare for the next time. Thereafter, the process returns to the main routine.

  On the other hand, if No in step T201, that is, if C1 = 5 and C2 = 5 is not reached, the process proceeds to step T202. Among these, (1) when the vehicle does not enter the tunnel and there is no change in the output values of the D and G side sensors due to the wind (including the case where the tunnel or wind cannot detect the change). (2) The case where changes due to wind can be detected, and (3) the case where changes due to wind have already been detected are included.

Therefore, in step T202, it is first determined whether or not the D-side wind detection flag Wd is set, that is, whether or not Wd = 1. This D-side wind detection flag Wd is set in step T206 described later (Wd = 1).
If Wd = 1 has already been set (Yes), the process proceeds to step T221 to calculate the D-side wind compensation value VADD. The calculation formula is given by VADD = [Sd (n) −Sd (n−16)] / 16.
The D-side wind compensation value VADD is calculated once every 16 cycles of acquisition of the D-side sensor output value Sd (n) every time the tunnel / wind detection subroutine by the D and G sensors is executed (16 × 0.5 = once every 8 seconds). The change that occurs in the D-side sensor output value Sd (n) due to the change in the wind speed is generally large at the beginning of the change in the wind speed, and gradually decreases and ends. Therefore, for the wind compensation value VADD for compensating for this change, it is preferable to calculate and select an appropriate value at each time point, rather than using a constant value, in order to more appropriately suppress the influence of fluctuation. it is obvious.
Thereafter, the process returns to the main routine.

On the other hand, in the case of No in step T202, the process proceeds to step T203, and this time, it is determined whether or not the G-side wind detection flag Wg is set, that is, whether or not Wg = 1. The G-side wind detection flag Wg is set at step T216 described later (Wg = 1).
If Wg = 1 has already been set (Yes), the process proceeds to step T222, and the G-side wind compensation value VADG is calculated. The calculation formula is given by VADG = [Sg (n−16) −Sg (n)] / 16.
The G-side wind compensation value VADG is also calculated once every 16 cycles of obtaining the G-side sensor output value Sg (n) for the same reason as the D-side wind compensation value VADD. Thereafter, the process returns to the main routine.
Thus, when the wind detection flag Wd or Wg is already set, that is, when the change due to the wind has already been detected (in the case of (3) described above), the D-side wind compensation value VADD or the G-side wind is detected. The compensation value VADG is calculated and the process returns to the main routine.

  However, if neither Wd = 1 nor Wg = 1 (Wd = Wg = 0), the process proceeds to step T204. In step T204, it is determined whether the D-side holding counter Cd is Cd ≧ 1 or the G-side holding counter Cg is Cg ≧ 1. When one of the two holding counters Cd and Cg has a value of 1 or more (Yes), the process returns to the main routine. In this case, since the deviation is allowed in the subroutine for recognizing the change timing deviation of the D and G sensors described above, both tunnel detection (step T231) and wind detection (steps T206 and T216) are performed. Is not appropriate.

  If No in step T204, that is, if Cd = Cg = 0, it is considered that it is not the above-described deviation allowable period, and therefore wind detection is performed. Specifically, first, in step T205, it is determined whether or not the D-side inclination recognition counter C1 is C1 = 5.

If C1 = 5 (Yes), the process proceeds to step T206. In this case, as a premise, the G-side inclination recognition counter C2 is not C2 = 5 (step T201), the wind detection flags Wd and Wg are not set (steps T202 and T203), and the holding counters Cd and Cg are 0. (Step T204). Therefore, if it is determined in this step T206 that C1 = 5 (Yes), the G-side sensor output value Sg (n) does not continue to decrease. Then, only the D-side sensor output value Sd (n) continues to change in the high concentration direction over a long period (at least 40 seconds or more in the present embodiment). Presumed to be a change. When the concentration of the oxidizing gas is increasing, except for the case of a tunnel or the like, it generally does not gradually occur over 40 seconds, and the concentration usually increases in a relatively short time. It has been found that the side sensor output value Sd (n) rises relatively quickly. Therefore, such a change in the high concentration direction over a long period of time is understood to be a wind-induced high direction change caused by a change in wind speed except for the tunnel.
Therefore, in step T206, the D-side wind detection flag Wd is set to Wd = 1.

  Subsequently, in step T207, a D-side base value Bd (n) is set. Specifically, the D-side base value Bd (n) is matched with the current D-side sensor output value Sd (n). Since the wind-induced high direction change is detected for the D-side sensor output value Sd (n), the currently obtained D-side sensor output value Sd (n) is obtained when there is no change in the wind speed. It is thought that there is a deviation from the hypothetical value that should have been. Therefore, in order to prevent or eliminate erroneous detection of the increase in oxidizing gas concentration due to the deviation, not the D-side sensor output value Sd (n) but the D-side base value Bd (n) is changed ( It has been resolved (in accordance with the current D-side sensor output value Sd (n)).

  Subsequently, in step T208, assuming that the concentration of the oxidizing gas is low and clean air, the LVd = 0 is set as the D-side gas detection signal LVd regardless of the current value. Regarding the D-side sensor output value Sd (n), since a change in the high concentration direction was observed over a long period of time, the D-side gas detection signal LVd is normally already LVd = 1 (high concentration). It is understood. However, this determination is based on a wind-induced high direction change, and it is considered that it was an erroneous determination to set LVd = 1. Therefore, this is canceled in step T208.

Subsequently, in step T209, a D-side wind compensation value VADD is calculated. The calculation formula is given by VADD = [Sd (n) −Sd (n−16)] / 16 as in step T221.
Thereafter, the process returns to the main routine.

In step T205, when the D-side inclination recognition counter C1 is not C1 = 5 (No), the process proceeds to step T215. In step T215, it is determined whether or not the G-side inclination recognition counter C2 is C2 = 5.
If C2 = 5 is not satisfied (No), the process returns to the main routine. This is a normal case (in the case of (1) above) in which the D and G sensor output values do not change due to wind, not entering the tunnel.

On the other hand, if C2 = 5 (Yes), the process proceeds to step T216. In this case, as a premise, the D-side inclination recognition counter C1 is not C2 = 5 (steps T201 and T205), the wind detection flags Wd and Wg are not set (steps T202 and T203), and the holding counters Cd and Cg Is 0 (step T204). Therefore, if it is determined in this step T216 that C2 = 5 (Yes), the D-side sensor output value Sd (n) does not continue to increase. Then, the fact that only the G-side sensor output value Sg (n) continues to change in the second high concentration direction for a long period (40 seconds or more) means that this change is the second wind-induced high direction change. It is estimated that. When the concentration of the reducing gas is increasing, it generally does not gradually increase over 40 seconds except in the case of tunnels, etc., and normally the concentration increases in a relatively short time. It has been found that the side sensor output value Sg (n) decreases relatively quickly. Therefore, the change in the second high-concentration direction over a long period of time is understood to be the second high-winding change caused by the wind speed change except for the tunnel.
Therefore, in step T216, the G-side wind detection flag Wg is set to Wg = 1.

  Subsequently, in step T217, a G-side base value Bg (n) is set. Specifically, the G-side base value Bg (n) is matched with the current G-side sensor output value Sg (n). As in the case of the D-side sensor output value Sd (n) described above (step T207), the currently obtained G-side sensor output value Sg (n) is obtained from a virtual value obtained when there is no change in the wind speed. Seems to be off. Therefore, in order to prevent or eliminate erroneous detection due to the deviation, not the G-side sensor output value Sg (n) but the G-side base value Bg (n) is changed.

  Subsequently, in Step T218, assuming that the reducing gas has a low concentration and clean air, the LVg = 0 is set as the G-side gas detection signal LVg regardless of the current value. It is understood that the G-side gas detection signal LVg is usually already LVg = 1 (high concentration). However, this determination is based on the second wind-induced high direction change, and it was considered that it was an erroneous determination to set LVg = 1, so this was canceled.

Subsequently, in step T219, a G-side wind compensation value VADG is calculated. The calculation formula is given by VADG = [Sg (n−16) −Sg (n)] / 16 as in step T222.
Thereafter, the process returns to the main routine.

  In this manner, in the gas detection device 210 of the present embodiment, the microcomputer 216 performs control using the two D-side gas sensor elements 211 and the G-side gas sensor element 221. Therefore, in the present embodiment, the relative speed (wind speed) between the two gas sensor elements 211 and 221 and the heater element 202 and the outside air changes due to a change in vehicle speed, a change in wind speed, and the like, and a D-side sensor output value Sd (n ) Can be detected from the duration of the change even when the wind-induced high density direction and the G-side sensor output value Sg (n) change in the second wind-induced high density direction. Further, it is possible to compensate for the influence of the change in the D-side sensor output value or the G-side sensor output value and appropriately detect the concentration change of the oxidizing gas and the reducing gas.

  Furthermore, in the gas detection device 210 of the second embodiment, the wind-induced high direction change or the second wind-induced high direction change accompanying the wind speed change is detected, and the influence of the change in the D-side sensor output value or the G-side sensor output value is detected. In addition to being able to compensate, the difference in characteristics between the two gas sensor elements 211 and 221 is used to change the wind-induced change in the D-side sensor output value Sd (n) or the G-side sensor output value Sg ( It is possible to detect whether or not the vehicle has entered the tunnel or the like by separating the high direction change caused by the second wind of n) and the change when entering the gas retention space such as the tunnel.

Next, in the gas detector 210 (system 200) according to the present embodiment, specific examples of changes in the D-side and G-side sensor output values Sd (n) and Sg (n) and the D-side and G-side bases corresponding thereto Changes in the values Bd (n), Bg (n), the D side and G side wind correction flags Wd and Wg, and the D side and G side gas detection signals LVd and LVg will be described with reference to FIGS.
Among these, FIG. 12 describes the data when the automobile equipped with the gas detection device 210 of the present embodiment is shifted from the low speed running to the high speed running and is run again in the low speed running pattern. On the other hand, FIG. 13 describes data when the vehicle travels in a long tunnel.
These include the virtual D-side base value ABd (n), the virtual G-side base value ABg (n) obtained in the case where the processing relating to wind detection and tunnel detection (steps T17 to T20) is not performed, and thus The virtual D side and G side gas detection signals ALVd and ALVg obtained in this case are also shown.

  Of these figures, the lowermost ones are the NO2 gas sensor (Interscan portable gas analyzer (Model No. 4150-2) and CO gas sensor (Interscan portable gas analyzer (Model No. 4140)). -1) is a graph showing changes in the NO 2 gas concentration (indicated by the alternate long and short dash line) and the CO gas concentration (indicated by the solid line) measured in D. Sensor output value Sd (n) on the D side Is indicated by a solid line, a D-side base value Bd (n) is indicated by a broken line, a virtual D-side base value ABd (n) is indicated by a one-dot chain line, and similarly below the G-side sensor output value Sg (n) is indicated by a solid line. The G-side base value Bg (n) is indicated by a broken line, and the virtual G-side base value ABg (n) is indicated by a one-dot chain line.

First, FIG. 12 will be described. As can be seen from the comparison between the NO2 gas concentration (indicated by the alternate long and short dash line) and the CO gas concentration (indicated by the solid line) in FIG. There is no change.
In the case shown in the figure, immediately after the start of the measurement shown in the figure (time 0 second), the vehicle shifts from low speed driving (city driving) to high speed driving (highway driving). Therefore, at time t0, D The side sensor output value Sd (n) starts to gradually increase. It is considered that the wind speed increases due to the increase in the speed of the automobile, the D-side gas sensor element 211 is cooled, and the sensor resistance value Rs1 increases. This slow increase in the D-side sensor output value Sd (n) continues for approximately 250 seconds or more.

However, since the increase in the D-side sensor output value Sd (n) is moderate, the D-side base value Bd (n) also follows gently, and the difference between the two (D-side difference value Dd (n)) Therefore, it takes time until it is determined to be Yes in step T40, and at time t1, the D-side gas detection signal LVd = 1 (step T41) is detected, and an increase in the concentration of the oxidizing gas is detected. However, as can be seen from the change in the NO 2 gas concentration, the detection of this oxidizing gas is a false detection.
Similarly, the virtual D side gas detection signal ALVd becomes ALVd = 1 at time t1.

Thereafter, at time t2, the D-side wind detection flag Wd is set to Wd = 1 (step T206). Since the increase in the D-side sensor output value Sd (n) has continued for 40 seconds (= 16 cycles × 5 times × 0.5 seconds) or more, this increase in the D-side sensor output value Sd (n) is caused by a change in the wind speed. This is because it is determined that (wind-induced high direction change). Therefore, at this timing (t2), the D-side base value Bd (n) is made to coincide with the D-side sensor output value Sd (n), and the D-side gas detection signal LVd once set to LVd = 1 at time t1 is cleared. (LVd = 0). Therefore, although not shown in the figure, the concentration signal LV output from the output terminal 218 of the gas detection device 210 is also cleared to LV = 0, and the flap 34 is rotated to the outside air introduction side.
On the other hand, since the wind-induced high direction change cannot be detected for the virtual D-side gas detection signal ALVd, LVd = 1 is continuously maintained after time t2, and the D-side sensor output value Sd (n) is inverted (decreased). It can be seen that for about 200 seconds until the time t3 when the operation starts, the erroneous detection state in which the concentration is high (LVd = 1) is maintained even though the concentration of the oxidizing gas is not high. Accordingly, during this time, LV = 1 is set, and the flap 34 is rotated to the inside air circulation side.

Thereafter, the state in which the D-side wind detection flag Wd is set to Wd = 1 continues until time t4 after time t3 when the D-side sensor output value Sd (n) is reversed (decreased). The side wind detection flag Wd is cleared (Wd = 0, step T704). At times t2 to t4, although not shown in the figure, the D-side wind compensation value VADD is updated every 16 samplings (every 8 seconds) at steps T209 and T221, and is corrected appropriately at each time point. A side base value Bd (n) is calculated. Therefore, during this period, the detection of the increase in the concentration of the oxidizing gas due to the influence of the change in the D-side sensor output value Sd (n) due to the change in the wind speed is not corrected. The correction of the D-side base value Bd (n) (Step T314). Thus, even during this period, the increase in the concentration of the oxidizing gas can be appropriately detected using the D-side difference value Dd (n).
After that, due to a slow fluctuation in the D-side sensor output value Sd (n), the wind-induced high direction change is detected at times t5 and t6, and the D-side wind detection flag Wd is set to Wd = 1.

Next, at time t7, when the vehicle changes from high speed to low speed, the temperature of the D side and G side gas sensor elements 211 and 221 rises as the wind speed decreases. The G-side sensor output values Sd (n) and Sg (n) continue to decrease slowly thereafter.
Due to the decrease in G-side sensor output value Sg (n) (change in the second high concentration direction), at time t8, the G-side gas detection signal LVg is set to LVg = 1 (step T61), and the reducing gas An increase in concentration is detected. However, as can be seen from the change in the CO gas concentration, the detection of the reducing gas is a false detection.
Similarly, the virtual G side gas detection signal ALVg becomes ALVg = 1 at time t8.

Thereafter, at time t9, the G-side wind detection flag Wg is set to Wg = 1 (step T216). Since the decrease in the G-side sensor output value Sg (n) has continued for 40 seconds or more, the decrease in the G-side sensor output value Sg (n) following time t7 is caused by a change in wind speed (second wind-induced high direction This is because it was determined that the change was made. Therefore, at this timing (t9), the G-side base value Bg (n) is matched with the G-side sensor output value Sg (n), and the G-side gas detection signal LVg once set to LVg = 1 at time 8 is cleared. (LVg = 0), false detection is eliminated. Therefore, the concentration signal LV of the output terminal 218 is also cleared to LV = 0, and the flap 34 is rotated to the outside air introduction side.
On the other hand, the virtual G-side gas detection signal ALVg cannot detect a wind-induced high direction change, and therefore continues to be LVg = 1 after time t9, even though the concentration of the reducing gas is not high. It can be seen that the misdetection state of determining high (LVg = 1) is continued.

From time t9 to time t10, the G-side wind detection flag Wg is once set to Wg = 0. During the period from time t9 to t10, the G-side wind compensation value VADG is updated every 16 samplings (every 8 seconds) in steps T219 and T222, and the G-side base value Bg (n) appropriately corrected at each time point. Is calculated. Therefore, at times t9 to t10, the G-side base value Bg (n) is detected because the detection of the concentration increase of the reducing gas becomes inappropriate due to the influence of the change in the G-side sensor output value Sg (n) due to the wind speed change. ) (Step T514). Thus, even during this period, it is possible to appropriately detect the concentration increase of the reducing gas by using the G-side difference value Dg (n).
It should be noted that wind-induced high direction change is detected at time t11 due to the slow fluctuation in the G-side sensor output value Sg (n) that continues thereafter, and the G-side wind detection flag Wg is set to Wg = 1.

  As described above, according to the gas detection device 210 (system 200) of the present embodiment, both the D-side sensor output value Sd (n) and the G-side sensor output value Sg (n) The resulting high direction change and the second wind-induced high direction change can be appropriately detected. Further, based on this, it is possible to compensate for the influence of changes in the D-side sensor output value Sd (n) or the G-side sensor output value Sg (n), and to detect appropriate increases in the concentrations of oxidizing gas and reducing gas. it can.

  Next, FIG. 13 will be described. This figure shows data when traveling in the tunnel for about 300 seconds from time t20 to t28. During this period, the NO2 gas concentration (dashed line) is gentle but almost linear. The concentration is increasing, and the concentration is rapidly decreasing near the tunnel exit (time t27). On the other hand, although the CO gas concentration (solid line) also varies somewhat, the concentration tends to increase with time (running in the tunnel), and the concentration rapidly decreases near the tunnel exit (time t27). ing.

After time t20 when the vehicle entered the tunnel, the D-side sensor output value Sd (n) starts to increase gently and the G-side sensor output value Sg (n) also starts to decrease gradually.
However, since the decrease in the G-side sensor output value Sg (n) is gradual, the G-side base value Bg (n) also gradually follows and decreases, and the difference between them (G-side difference value Dg (n)) ) Does not increase, it takes time to be determined as Yes in step T60, and at time t21 when the G-side sensor output value Sg (n) rapidly decreases, the G-side gas detection signal LVg = 1 (step T61). ), And an increase in reducing gas concentration is detected. Similarly, the virtual G side gas detection signal ALVg is ALVg = 1 at time t21.

On the other hand, since the rise of the D-side sensor output value Sd (n) is also gentle, the D-side base value Bd (n) also rises following gently, and the difference between the two (D-side difference value Dd (n)) Since the value does not increase, it takes time to determine Yes in step T40. Therefore, after the tunnel detection described below is performed and the coefficient of the formula for calculating the D-side base value Bd (n) is changed, the D-side gas detection signal LVd = 1 (step T41) is gradually obtained at time t23. An increase in the concentration of oxidizing gas is detected.
On the other hand, since the tunnel detection is not performed for the virtual D side gas detection signal ALVd, the coefficient is not changed, and ALVd = 0, that is, the increase in concentration remains undetectable after time t23.

At time t22 earlier than this time t23, the tunnel detection flag TN is set to TN = 1 (step T231). About 60 seconds have elapsed from time t20. The behavior of the D-side sensor output value Sd (n) and the G-side sensor output value Sg (n) near the time t20 can be understood by observing this figure, but after the time t20, the G-side sensor output value Sg (n) is Although gradually decreasing, it can be seen that the D-side sensor output value Sd (n) has been maintained at a substantially constant value for about 10 to 20 seconds from time t20. That is, in the example of this figure, the increase in the D-side sensor output value Sd (n) occurred slightly later than the decrease in the G-side sensor output value Sg (n). In addition, after time t21, the G-side sensor output value Sg (n) rapidly decreases and then slightly reverses (increases) until time t22. Therefore, in this example, the second duration of the change in the G-side sensor output value in the second high concentration direction is considered to be about 50 seconds from time t20. On the other hand, it is considered that the duration of the change in the D-side sensor output value in the high concentration direction was about 40 seconds from about 10 seconds before time t21 to time t22. In this example, it is detected that the gas detection device 210 and the vehicle equipped with the gas detection device 210 have entered the tunnel by such a continuation period and the second continuation period.
In the present embodiment, as described above, since the D, G sensor change timing deviation recognition subroutine (step T19: T901-916) is included, the G-side holding counter Cg (step T912) is used. Since the timing shift is recognized, a gas retention space such as a tunnel can be appropriately detected at time t22.

As for the D-side sensor output value Sd (n) used in this embodiment, both the direction in which this changes when the wind speed increases and the direction in which it changes when the concentration of the oxidizing gas increases are both. The value is increasing. For this reason, using only this D-side sensor output value Sd (n) and examining only the duration of the increasing tendency of the value, it is a wind-induced high direction change due to an increase in the wind speed, or it entered the tunnel. However, it is impossible to distinguish whether the concentration of the oxidizing gas gradually increases.
However, for the G-side sensor output value Sg (n), the direction in which the G-side sensor output value Sg (n) changes when the wind speed increases is opposite to the direction in which the G-side sensor output value Sg (n) changes when the concentration of the reducing gas increases. Specifically, when the wind speed increases, the G-side sensor output value Sg (n) increases or does not change much (see FIG. 12). On the other hand, when the concentration of the reducing gas increases, the G-side sensor output value Sg (n) decreases.
Therefore, if the wind speed increases and the value of the D-side sensor output value Sd (n) gradually increases, the G-side sensor output value Sg (n) also increases or does not change much. On the other hand, when the value of the D-side sensor output value Sd (n) gradually increases after entering a tunnel or the like, the G-side sensor output value Sg (n) decreases as the concentration of the reducing gas increases. To do. Thus, by using the gas sensor elements 211 and 221 having two different characteristics, it is discriminated whether the change in the D-side and G-side sensor output values is due to the wind speed change or the entry into the tunnel or the like. Is able to.

Further, at time t22, since TN = 1, step T24 is set to Yes, and in step T25, coefficients relatively smaller than step T26, k1, h1, k4, and h4 are selected, and step T314 is selected. In 514, the D-side base value Bd (n) and the G-side base value Bg (n) are calculated using this. Therefore, in FIG. 13, as can be easily understood by comparing with the virtual D-side base value ABd (n) and the virtual G-side base value ABg (n) whose coefficients are not changed, the stay after time t22 In the space approach period, changes in the D-side base value Bd (n) and the G-side base value Bg (n) are further slowed down.
Conversely, after this time t22, the difference (D-side difference value Dd (n)) between the D-side sensor output value Sd (n) and the D-side base value Bd (n) increases, and at time t23, the step T40 is satisfied and LVd = 1 (step T42).

In this figure, it is set as tunnel detection (TN = 1) in the time t22-t27 (staying space approach period). Accordingly, since the changes in the D-side base value Bd (n) and the G-side base value Bg (n) are slowed as described above, the G-side gas detection signal LVg includes the times t22 to t27. LVg = 1 is set over t27. Even in the D-side gas detection signal LVd, LVd = 1 is set for a period from time t23 slightly delayed from time t22 to time t27.
On the other hand, the virtual G side gas detection signal ALVg is ALVg = 0 at times t24 to t25 and t26 to 27 among the times t21 to t27. That is, during this period, it is erroneously determined that the concentration of the reducing gas is low. This is because the virtual G-side base value ABg (n) follows the G-side sensor output value Sg (n) relatively earlier than the G-side base value Bg (n) at times t22 to t27. Since they change, these differences are smaller than the second difference value Dg (n). For this reason, it is judged as No in step T54 at times t24 and t26, and the virtual LVg is cleared in step T56 (ALVg = 0). Conversely, in the gas detection device 210 of the present embodiment, since the coefficients for calculating the D-side base value Bd (n) and the G-side base value Bg (n) are changed at time t22 (steps T24 and T25), It can be said that such misjudgment could be prevented.

Thereafter, at time t27, when the concentration of the reducing gas rapidly decreases and the G-side sensor output value Sg (n) increases rapidly, the difference between the G-side sensor output value Sg (n) and the G-side base value Bg (n) is obtained. The second difference value Dg (n) becomes equal to or less than TH24 (No in Step T55), the G-side gas detection signal LVg is set to 0 (Step T56), the tunnel detection flag TN is cleared (TN = 0) (58), The tunnel end recognition flag TNE is cleared (step T59).
In this example, it can be understood that the actual tunnel exited at time t28 immediately after time t27, and that the tunnel end detection was also appropriate.

  Thus, according to the gas detection device 210 (system 200) of the present embodiment, the duration of the change in the high concentration direction of the D-side sensor output value Sd (n) and the G-th sensor output value Sg (n) Using the second duration of the two-concentration high-direction change, it is possible to detect entry into a gas retention space such as a tunnel. In addition, by utilizing the difference in characteristics between the D-side gas sensor element 211 and the G-side gas sensor element 221, even if the duration time of the similar change in the high concentration direction of the D-side sensor output value Sd (n) occurs, it depends on the change in the wind speed. It can also be distinguished whether it is due to entry into a tunnel or the like.

In the above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.
For example, in the above embodiment, the change in the gas concentration is detected using the difference value Dd (n) between the D-side sensor output value Sd (n) and the D-side base value Bd (n) (see step T32). However, the D-side sensor output value Sd (n), the D-side base value Bd (n), and the ratio L (n) can also be used. The same applies to the G-side sensor output value.

In addition, as a formula for obtaining the D-side and G-side base values Bd (n) and Bg (n), a calculation formula different from the embodiment can be used. For example, a calculation formula in a format in which the third term for emphasizing the change is eliminated can be used.
In steps T24 to T26, coefficients of the calculation formulas for obtaining the D-side and G-side base values Bd (n) and Bg (n) are selected. For example, when Yes is determined in step T24 (residence space) In the approach period), the D-side and G-side base values may be calculated using different calculation formulas. Further, the threshold values TH22 and TH24 can be changed to other values.

  In the above-described embodiment, the change in the wind speed causes a change in the same direction as the concentration of the oxidizing gas or the reducing gas increases (wind-induced high direction change or second wind-induced high direction change). Only in this case, this was detected, and the base value and the like were corrected using the D-side and G-side wind compensation values. However, even when the gas concentration changes in the same direction as the decrease in the wind speed, this may be detected and the base value or the like may be corrected using the wind compensation value or the like.

It is explanatory drawing which shows the outline | summary of the gas detection apparatus concerning embodiment, and the autoventilation system for vehicles. It is explanatory drawing which shows the flow of control in the vehicle autoventilation system concerning embodiment. It is FIG. 1 of the explanatory drawings which shows the flow of the main routine of the control in a microcomputer among the gas detection apparatuses concerning embodiment. It is FIG. 2 of the explanatory drawings which show the flow of the main routine of the control in a microcomputer among the gas detection apparatuses concerning embodiment. It is FIG. 3 of the explanatory drawings which show the flow of the main routine of the control in a microcomputer among the gas detection apparatuses concerning embodiment. It is explanatory drawing which shows the content of D element-inclination & wind correction completion | finish judgment routine among control in a microcomputer concerning embodiment. It is explanatory drawing which shows the content of G element-inclination & wind correction completion | finish judgment routine among control in a microcomputer concerning embodiment. It is explanatory drawing which shows the content of the D and G element change timing shift recognition routine among control in a microcomputer concerning embodiment. It is explanatory drawing which shows the content of the tunnel by a D and G element, and the wind detection routine among control in a microcomputer concerning embodiment. It is explanatory drawing which shows the content of the calculation routine of D side base value Bd (n) among control in a microcomputer concerning embodiment. It is explanatory drawing which shows the content of the calculation routine of G side base value Bg (n) among control in a microcomputer concerning embodiment. Changes in the D sensor output value, the G sensor output value, the D side base value, the G side base value, and the like when a wind-induced change occurs when the gas detection device according to the embodiment is mounted on an automobile and traveled It is explanatory drawing which shows. Changes in the D sensor output value, the G sensor output value, the D side base value, the G side base value, etc. when traveling in a tunnel among the cases where the gas detection device of the embodiment is mounted on an automobile and traveled. It is explanatory drawing shown.

Explanation of symbols

201 Gas Sensor 202 Heater Element Rh Heater Resistance 200 Auto Ventilation System 210 for Vehicle Gas Detector 211 D-side Gas Sensor Element (Gas Sensor Element)
221 G side gas sensor element (second gas sensor element)
212, 222 Detection resistance Rs1, Rs2 Sensor resistance value Rd1, Rd2 Detection resistance value Pd1, Pd2 Operating point 213, 223 Buffer 214, 224 Sensor resistance value conversion circuit 215, 225 A / D converter 216 Microcomputer 217, 227 Input terminal 218 Output terminal 219 D side sensor output value acquisition circuit (acquisition means)
229 G side sensor output value acquisition circuit (second acquisition means)
20 Electronic control assembly 21 Flap drive circuit 31, 32, 33 Duct 34 Flap Sd (n) D side sensor output value (sensor output value)
Sg (n) G side sensor output value (second sensor output value)
Bd (n) D side base value (reference value)
Bg (n) G side base value (second reference value)
Dd (n) D-side difference value Dg (n) G-side difference value LV Concentration signal LVd D-side gas detection signal (concentration signal)
LVg G side gas detection signal (second concentration signal)
VADD D side wind compensation value VADG G side wind compensation value Wd, Wg Wind detection flag TN Tunnel detection flag TNE Tunnel end detection flags TH21, TH22, TH23, TH24 Threshold value

Claims (7)

A gas sensor element whose sensor resistance value changes in accordance with a change in concentration of a specific gas in the environmental gas;
Acquisition means for acquiring a sensor output value corresponding to the sensor resistance value;
A second gas sensor element whose second sensor resistance value changes in accordance with a change in concentration of a second specific gas other than the specific gas in the environmental gas;
Second acquisition means for acquiring a second sensor output value corresponding to the second sensor resistance value;
The gas sensor element and the second gas sensor element use the duration of the change in the sensor output value in the high concentration direction and the second duration of the change in the second concentration output in the second concentration high direction. A gas detection apparatus comprising: a residence space entry determination unit that determines whether or not the gas has entered the gas residence space. The gas detection device according to claim 1,
When the duration continues for a predetermined period or longer, and the second duration is equal to or longer than the second allowable period and less than the second predetermined period, at least the second sensor output value changes in the second high concentration direction. Is considered to have continued for more than the predetermined period over the second extension period until the second continuous period becomes equal to or greater than the second predetermined period.
When the second continuation period continues for the second predetermined period or longer, and the continuation period is equal to or longer than the first allowable period and less than the predetermined period, the sensor output value continues to change in the high concentration direction. A gas detecting device including a deviation allowing means for considering that the second continuation period continues for the second predetermined period or more over a first extension period until the continuation period becomes the predetermined period or more. The gas detection device according to claim 1 or 2, wherein
Using the sensor output value, a concentration high / low determination means for determining a high concentration indicating that the concentration of the specific gas has increased or a low concentration indicating that the concentration has decreased ,
Using the second sensor output value, a second concentration high / low determination means for determining a high concentration indicating that the concentration of the second specific gas has increased or a low concentration indicating that the concentration has decreased ;
Since it is judged that enters the gas retaining space in the retaining space entry judging means determines the low the concentration of the specific gas in the concentration height determining means, and said second specified gas in the second concentration height determining means of at least one of a determination that the concentration low, the gas detection apparatus and a retaining space entry canceling means for canceling the determination that has entered to the gas retention space. The gas detection device according to claim 3,
After determining that the gas staying space has been entered by the staying space approach determining means, the concentration level is increased over the staying space entering period until the determination that the staying space approach releasing means has entered the gas staying space is canceled. wherein the inhibiting concentration low determination suppressing means the concentration low determination of the specific gas in the determination means,
Over the retaining space entry period, gas detection apparatus and a second density lower determination suppressing means for suppressing the concentration low is determined in the second specific gas in the second concentration height determining means. The gas detection device according to claim 4,
A reference value calculating means for calculating a current reference value;
Second reference value calculating means for calculating a current second reference value,
The concentration level determination means includes:
In comparison with the current sensor output value and the current reference value, it is determined that the concentration of the specific gas is high or low ,
The second density high / low determination means includes:
The current second sensor output value is compared with the current second reference value to determine whether the concentration of the second specific gas is high or low ,
The low concentration determination suppressing means includes
Reference value change suppression means for suppressing a change in the current reference value calculated in the reference value calculation means,
The second low concentration determination suppression means includes
A gas detection device as second reference value change suppression means for suppressing a change in the current second reference value calculated by the second reference value calculation means. The gas detection device according to claim 5,
The reference value change suppressing means is a reference value calculation coefficient changing means for changing a coefficient of a calculation formula used in the reference value calculating means,
The gas detection device, wherein the second reference value change suppression means is second reference value calculation coefficient changing means for changing a coefficient of a calculation formula used in the second reference value calculation means. The vehicle autoventilation system containing the gas detection apparatus of any one of Claims 1-6.

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